جهانشیر امینی

During the observations over nurseries and almond gardens of Kermanshah Province in 20 I 0-20 II, sap lings and fertile trees suspected to infection by Phytophlhora and Pythium and the so il around their root and foot were sampled. A tier culturing these samples on common and semi-sel ect ive media, some isolates of Pythium (sensu /ato) and Phytophthora were obtained. These iso lates were identitied based on their morphological and seve ral physiological characteristics. Pathogenicity tests were performed on excised shoots and seed li ngs In vi1ro and In vivo respectively. In this research, 12 isolates, belong to 4 species including Ph\'tophthora cactomm, Pvthium aphanidermatum, Ovatisporangium helicoides and Pythium group-G were identified. In pathogeniciry tests on excised shoots, highly significant difference was found among the treatments based on the rate of disease extension. In this experiment the most disease extension was induced by P. cactorum followed by O.helicoides. There was no significant difference for disease development of P.aphanidermatum and P. group-G when compared to the control. In pathogenicity test under greenhouse condition, P. cactorum isolates caused seed ling death atier 7 days, but the symptoms of seedling death appeared a tier 40 days, when almond seedl ings were exposed to P.aphanidermatum and O.helicoides. P. group-G did not make any pathogenicity on almond seedl ings in both experiments. This is the first report of identification and pathogenicity of 0. helicoides in Iran.